scsi: ufs: ufshpb: Make eviction depend on region's reads
authorAvri Altman <avri.altman@wdc.com>
Mon, 12 Jul 2021 09:50:32 +0000 (12:50 +0300)
committerMartin K. Petersen <martin.petersen@oracle.com>
Sun, 1 Aug 2021 20:05:14 +0000 (16:05 -0400)
In host mode, eviction is considered an extreme measure. Verify that the
entering region has enough reads, and the exiting region has fewer reads.

Link: https://lore.kernel.org/r/20210712095039.8093-6-avri.altman@wdc.com
Reviewed-by: Daejun Park <daejun7.park@samsung.com>
Signed-off-by: Avri Altman <avri.altman@wdc.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
drivers/scsi/ufs/ufshpb.c

index a330c49..912bc6e 100644 (file)
@@ -17,6 +17,7 @@
 #include "../sd.h"
 
 #define ACTIVATION_THRESHOLD 8 /* 8 IOs */
+#define EVICTION_THRESHOLD (ACTIVATION_THRESHOLD << 5) /* 256 IOs */
 
 /* memory management */
 static struct kmem_cache *ufshpb_mctx_cache;
@@ -1056,6 +1057,13 @@ static struct ufshpb_region *ufshpb_victim_lru_info(struct ufshpb_lu *hpb)
                if (ufshpb_check_srgns_issue_state(hpb, rgn))
                        continue;
 
+               /*
+                * in host control mode, verify that the exiting region
+                * has fewer reads
+                */
+               if (hpb->is_hcm && rgn->reads > (EVICTION_THRESHOLD >> 1))
+                       continue;
+
                victim_rgn = rgn;
                break;
        }
@@ -1223,7 +1231,7 @@ unlock_out:
 
 static int ufshpb_add_region(struct ufshpb_lu *hpb, struct ufshpb_region *rgn)
 {
-       struct ufshpb_region *victim_rgn;
+       struct ufshpb_region *victim_rgn = NULL;
        struct victim_select_info *lru_info = &hpb->lru_info;
        unsigned long flags;
        int ret = 0;
@@ -1250,7 +1258,15 @@ static int ufshpb_add_region(struct ufshpb_lu *hpb, struct ufshpb_region *rgn)
                         * It is okay to evict the least recently used region,
                         * because the device could detect this region
                         * by not issuing HPB_READ
+                        *
+                        * in host control mode, verify that the entering
+                        * region has enough reads
                         */
+                       if (hpb->is_hcm && rgn->reads < EVICTION_THRESHOLD) {
+                               ret = -EACCES;
+                               goto out;
+                       }
+
                        victim_rgn = ufshpb_victim_lru_info(hpb);
                        if (!victim_rgn) {
                                dev_warn(&hpb->sdev_ufs_lu->sdev_dev,